Polygalacturonase in Tomato Fruits and the Induction of Ripening

1982 ◽  
Vol 9 (2) ◽  
pp. 171 ◽  
Author(s):  
CJ Brady ◽  
G Macalpine ◽  
WB McGlasson ◽  
Y Veda
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Tomato Fruit ◽  
Water Soluble ◽  
Enzyme Protein ◽  
Tomato Fruits ◽  
High Molecular Weight Form ◽  
Fruit Samples ◽  
Highly Correlated ◽  
Molecular Weight Form

Endopolygalacturonase (EC 3.2.1.15) activity, endopolygalacturonase protein detected immunologically and water-soluble uronide were measured in tomato fruit samples (cv. Rutgers) at different stages of ripening. Endopolygalacturonase activity and endopolygalacturonase protein were only detected in samples in which ripening had been initiated for 2 or more days. Enzyme activity and enzyme protein increased during ripening and were highly correlated. A high molecular weight form of the enzyme appeared 2 or 3 days after ripening was initiated. Lower molecular weight forms of endopolygalacturonase appeared later and eventually accounted for most of the enzyme protein. The content of water-soluble uronide did not increase until fruit had been ripening for 4 or more days. It is concluded that endopolygalacturonase is not involved in the initiation of ripening.

Spreading of microinjected horseradish peroxidase to nondescendant cells in embryos of Patella (Mollusca, Gastropoda)

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 713-722
Author(s):  
W.M. Kuhtreiber ◽  
F. Serras ◽  
J.A.M. van den Biggelaar
Keyword(s):  
Molecular Weight ◽  
Stem Cell ◽  
Horseradish Peroxidase ◽  
High Molecular Weight ◽  
Fluorescein Isothiocyanate ◽  
Contact Phase ◽  
High Molecular Weight Form ◽  
Contact Stage ◽  
Fluorescein Isothiocyanate Dextran ◽  
Molecular Weight Form

We have injected horseradish peroxidase (HRP) and fluorescein-isothiocyanate dextran (FD) into cells and into the blastocoelic cavity of Patella vulgata embryos, before and during the interval between 5th and 6th cleavage, in which the mesodermal stem cell is determined by means of interactions between the central 3D macromere and the contacting animal micromeres. Intracellular injections of HRP at different stages showed that, whereas before this contact phase no spreading of label was observed, a clear intercellular transfer of HRP was found after the contact was established. Control experiments showed that it was HRP in its intact, high molecular weight form that was transferred in the living embryo. Injections of HRP into the blastocoelic cavity gave essentially the same results. In these cases, the HRP was taken up by the cells from contact stage onwards. When FD was injected into the blastocoelic cavity, no uptake was observed, not even after prolonged presence of FD in it. However, when HRP and FD were mixed, both were taken up, starting at contact stage. Differences in labelling pattern of HRP, as compared with FD, and a shift of the FD fluorescence after uptake, suggest that receptor-mediated endocytosis is involved. The possible morphogenetic significance of the transfer mechanism is discussed.

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